Spark plug



F. B. HEWEL Sept. 12; 1939.

SPARK PLUG Filed March 21, 1936 H9. e /9 14 Hg. /5

INVENTOR Fran/KB. Hewe/ wvzilw 12.

. ATTORNEY Patented Sept. 12, 1939 UNITED STATES eTENr orFicE 11 Claims.

My invention relates to spark plugs for use in internal combustion engines.

One object of my invention is to provide an unusually effective and durable spark plug for 6 such use.

Another object of my invention is to provide a spark plug which shall be self-cleaning and self-cooling during its normal operation.

A more specific object of my invention is to provide a sleeve or cage member enclosing the two terminals or electrodes of the spark plug, the sleeve member being apertured to permit a minor explosion therein for causing the spark flame to spread over the top of the combustion chamber.

Another object of my invention is to provide a spark plug having a simple interchangeable terminal block, whereby the conductor cable leading to the spark plug may be rapidly assembled in the terminal block at an angle that best suits 20 the convenience of the operator.

' Other objects of my invention will become evident from the following detailed description, taken in conjunction with the accompanying drawing, wherein:

Figure 1 is a View in side elevation of a spark plug and terminal block therefor constructed in accordance with my present invention and applied to a cylinder head;

Fig. 2 is a view in longitudinal section of the spark plug shown in Fig. 1, the terminal block being shown in one of its other positions;

Fig. 3 is a bottom plan view of my spark plug;

Fig. 4 is a view in side elevation of the sleeve or cage member utilized in my spark plug;

Fig. 5 is a View of this sleeve or cage member taken at right angles to the view of Fig. 4;

Fig. 6 is a view in longitudinal section of the sleeve member taken along the line VI-VI of Fig. 5;

Figs. 7 and 8 are views, respectively, in top plan and in bottom plan of the sleeve member shown in Fig. 4;

Figs. 9 and 10 are, respectively, top and bottom plan views of my terminal block;

Fig. 11 is a View in longitudinal section taken along the line XI-XI of Fig. 9;

Fig. 12 is a view in end elevation of the terminal block;

Figs. 13 and 14 are detail views, taken at right 50 angles to each other, of the plug terminal utilized in my terminal block; and I Fig. 15 is a longitudinal section along the line XV-XV of Fig. 13.

Referring to the drawing, the structure here 65 shown comprises my spark plug I, which is detachably secured to the cylinder head 2 of an internal combustion engine in any usual or suitable manner as by being screwed thereinto in conjunction with a gasket 3.

The illustrated spark plug comprises a centrally located terminal or electrode 4 which extends through and beyond the two ends of a cylindrical insulating member 6, the terminal 3 being set into a solid insert 5 at the upper end of the insulator which is provided with a conical lower end 1. A shell or body member 8 cooperating with a nut member l8 serves to enclose the lower half of the insulator 6 and is provided at its lower end with an externally threaded portion 9 for screwing into the cylinder head 2, as indicated in Fig. 1.

The cooperating or second electrode or terminal Iii is suitably electrically secured at the lower end of the shell member 8 and is turned at right angles to extend a short distance below the lower end of the central terminal or electrode 4, in accordance with a familiar practice.

A metallic sleeve or cage member H, preferably made of copper, has an upper portion [2 that is substantially conical and a lower portion 13 that is substantially cylindrical, the lower or outer end of the sleeve or cage member being, substantially closed by an end plate or disc l4, except for a slot 15 for a purpose to be hereinafter described. In addition, the expcsed lower or outer end of the sleeve or cage member I! is provided with a plurality of apertures or openings It in the side walls thereof close to the bottom closure 14, one of these openings [6, as clearly shown in Figs. 5 and 6, being contiguous with the slot 15 in the bottom closure I l, thereby permitting ready insertion of the right-angle terminal Ill through these contiguous openings in assembling the sleeve or cage member II in its final position. In addition, the openings 16, in conjunction with the substantially closed end member it, serve other functions to be hereinafter described.

It will be noted that the upper flared end of the sleeve or cage member I! closely fits against an annular shoulder l9 within the shell member 8, being closely held against that shoulder by an adjacent portion of the insulator 8 so that the sleeve or cage member is firmly held in its proper centrally located position and at the same time, by reason of its good thermal contact with the shell member 8, serves to conduct heat from the spark plug terminals through the sleeve or cage member H to the shell member 8 and thence to the atmosphere. In order to provide a certain convection of heat for further cooling the parts, a plurality of small openings I! may be provided in the conical portion I2 of the sleeve or cage member ll, thereby permitting a circulation of air or vapor from the one side to the other of the sleeve or cage member, which is slightly spaced from the lower conical end 1 of the insulator 6. i

It will be noted, therefore, that the sleeve or cage member II at its upper or inner end acts not only as a heat conductor to the outer shell, but also as a gasket between the outer shell and the insulator, and at the same time the sleeve or cage member I I may be very readily taken out when it is necessary to either replace it or a new insulator 6 and electrode 4.

The operation of my spark plug may be set forth as follows: When the spark plug fires within the combustion chamber, a minor explosion first occurs within the lower partly enclosed end of the sleeve or cage member II, the openings l5 and I6, however, causing the spread of the spark flame therethrough over the entire top of the combustion chamber. This action at the same time creates a partial vacuum which sets up a circulation of vapor through the openings 1 5 and I6, which vapor further circulates through the lower and upper portions of the sleeve or cage member ll, including the small openings IT, as previously described, thereby serving to effectively cool the electrode and insulator members.

Moreover, the above-noted minor explosion within the sleeve or cage member assists in keeping the spark plug parts clean and free from carbon, oil and tetra-lead, the bottom closure l4 being of material value in this self-cleaning operation of my spark plug.

My spark plug also includes and especially advantageous interchangeable terminal block 20, having a flattened portion 2| containing threaded openings 21 on four different faces for selectively engaging the threaded upper end of central electrode 4, and further comprises a cylindrical portion 22 having an internal socket 25 for receiving the conducting outer end or plug portion 23 of a cable or conductor 24.

The flattened internally threaded portion 2| is preferably rectangular in shape, except for a cut-off corner face 26, and this face 26 together with the two adjacent small faces and the 'remaining longer face all are provided with threaded apertures 21 of such a size as to screw over the threaded end of the central electrode 4. As a result, the terminal block and cable may be installed on the spark plug in any one of four different positions, whichever is the more convenient from the standpoint of the operator, two of these positions being shown in Figs. 1 and 2, respectively, and the other positions respectively corresponding to placing the small face at the left of cut-off face 26 in a horizontal position and placing the opposite longer face in a horizontal position, so that the openings 21 in these faces, which may conveniently constitute a single continuous opening, may respectively engage the threaded upper end of the central terminal 4.

The cable or conductor 24 (see Figs. 13, 14 and 15) may be of any suitable type, such as a familiar rubber-covered cable including a central strand of wires 28, which wires are separated at the cut-off end of the cable and bent over the sides thereof in position to be contacted by the U-shaped plug terminal 23, which, in addition to engaging these wires at the sides of the cable, has its ends bent or otherwise adapted to grip the rubber to definitely position the terminal 23. At the same time a pin 29 is struck up from the central or end portion of the terminal 23, which pin may be forced downwardly between the wires of the strand, thus serving to effect further electrical contact and mechanical positioning of the terminal. The plug 23 is also provided with a peripheral ridge 30 which serves to frictionally and resiliently maintain the cable plug in position in the socket 25, thereby providing good electrical contact and at the same time ready mechanical assembly or disassembly.

It will be noted that I have thus provided a spark plug which is effective, durable and convenient in construction, installation and operation, involving a minimum number of parts for providing the desired functions, partly by reason of the fact that a single sleeve or cage member II is adapted to perform the multiple functions of a heat conductor, a gasket, a flame spreader and means for cleaning and cooling the associated parts, and partly because of the fact that a single terminal block and cable may be secured to the spark plug in any one of four different positions.

I do not wish to be restricted to the specific structural details or arrangement of parts herein provided, as various modifications thereof may be effected without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed thereon as are indicated in the appended claims.

I claim as my invention:

1. A spark plug having an insulated central firing terminal, a second firing terminal extending at substantially right angles thereto, and a member of general conical shape enclosing said terminals, said member being electrically connected to one of said terminals but physically distinct from both of them and having a plurality of apertures located adjacent thereto.

2. A spark plug having an insulated central firing terminal, a second firing terminal extending at substantially right angles thereto, and a metallic closed-end sleeve member enclosing said terminals, said member being electrically connected to one of said terminals but physically distinct from both of them and having an opening in its closed end and a plurality of openings in its sides near said end.

3. A spark plug having an insulated central firing terminal, a second firing terminal extending at substantially right angles thereto, and a separable metallic closed-end sleeve member having a side wall and its closed end contiguously apertured to receive said right angle terminal.

'4. A spark plug having an insulated central firing terminal, a second firing terminal extending at substantially right angles thereto, and a separable metallic closed-end sleeve member having a side wall and its closed end contiguously apertured to receive said right angle terminal, the side walls of said member having further apertures in substantialy the same plane as the first-named side wall aperture.

5. A spark plug having a central terminal, an insulator surrounding said terminal, a metallic shell surrounding said insulator, a second terminal extending from an end wall of said shell at substantially right angles to said central terminal, and an apertured metallic member enclosing said terminals and disposed between said insulator and said shell.

6. A spark plug having a central terminal, an insulator surrounding said terminal, a metallic shell surrounding said insulator, a second terminal extending from an end wall of said shell at substantially right angles to said central terminal, and a member of general conical shape enclosing said terminals and having a plurality of apertures located adjacent thereto, said member being disposed between said insulator and said shell.

7.- A spark plug having a central terminal, an insulator surrounding said terminal, a metallic shell surrounding said insulator, a second terminal extending from an end wall of said shell at substantially right angles to said central terminal, and a metallic closed-end sleeve member enclosing said terminals and having an opening in its closed end and a plurality of openings in its sidesnear said end, said member being disposed between said insulator and said shell.

8. A spark plug having a central terminal, an insulator surrounding said terminal, a metallic shell surrounding said insulator, a second terminal extending from an end wall of said shell at substantially right angles to said central terminal, and a metallic closed-end sleeve member having a side wall and its closed end contiguously apertured to receive said right angle terminal, said member being disposed between said insulator and said shell.

9. A spark plug having a central terminal, an insulator surrounding said terminal, a metallic shell surrounding said insulator, a second terminal extending from an end wall of said shell at substantially right angles to said central terminal, and a metallic closed-end sleeve member having a side wall and its closed end contiguously apertured to receive said right angle terminal, the side walls of said member having further apertures in substantially the same plane as the first-named side wall aperture, said member being disposed between said insulator and said shell.

10. A spark plug having an insulated central firing terminal, a second firing terminal extending at substantially right angles thereto, and

'means for eiTecting self-cleaning and cooling of said terminal comprising a closed-end sleeve enclosing said terminals, said sleeve being electrically connected to one of said terminals but physically distinct from both of them and having apertures in its end and sides near said terminals for causing outward spread of flame and passage of cooling vapor.

11. A spark plug having a central firing terminal, an insulator surrounding said terminal, a metallic shell surrounding said insulator, a second firing terminal extending from an end wall of said shell at substantially right angles to said central terminal, and means for efiecting selfcleaning and cooling of said terminals comprising a separable closed-end sleeve disposed around said insulator in heat-conducting relation with said shell, said sleeve at its closed end enclosing said terminals and having contiguous apertures in its end face and side wall for permitting passage of said right angle terminal during assembly of the spark plug and also having other apertures in its side walls for causing a minor explosion within said sleeve to spread the spark flame over the top of a combustion chamber and set up a circulation of cooling vapor through said side wall apertures.

FRANK B. HEWEL. 

